1. Field of the Invention
The present invention relates to a print medium identifying device and method for identifying the type of print media used for a printing apparatus, as well as a printing apparatus comprising the print medium identifying device.
2. Description of the Related Art
Printing apparatuses use electrophotographic systems, wire dot systems, ink jet printing systems, and many other systems as output apparatuses for image forming systems which attach colored toner or ink to a print surface of a print medium to form a color image or the like, and then discharges the print medium on which the image is formed. Of these printing apparatuses, printing apparatuses based on the ink jet system require only a small number of steps to form an image on a print medium; with the ink jet system, a print head ejects ink directly to a print medium. Accordingly, these printing apparatuses have the advantages of, for example, requiring only low running and manufacturing costs, being suitable for color printing, and making little noise during a printing operation. The ink jet printing apparatus thus gathers much attention in various markets for such printing apparatuses ranging from clerical to domestic ones. Thus, in recent years, output apparatuses to which the ink jet system is applied have been employed in a large number of image forming systems such as printers, facsimile machines, and copiers.
However, a variety of print media are used in a printing apparatus employing the ink jet system; the print media vary in the capability of absorbing ink. Thus, in the printing apparatus based on the ink jet system, with which image quality is significantly affected depending on the type of print media used, the type of the print media used is identified before a printing operation is started. Then, the printing operation is controlled on the basis of the result of the identification.
A well-known conventional method for identifying the type of print media irradiates the surface of a print medium with light to measure light regularly reflected by the print medium. This identifying method focuses on a variation in the surface roughness of print media to measure the quantity of light regularly reflected by each print medium. The method thus acquires glossiness data on the print medium and then compares the glossiness data acquired with prestored data on a threshold for the quantity of light regularly reflected. The method thus identifies the type of the print medium (Japanese Patent Application Laid-Open No. 06-015861 (1994)).
However, a variety of print media varying in surface smoothness or the type of coating agent are used for the printing apparatus based on the ink jet system in accordance with applications. Accordingly, when the method according to Japanese Patent Application Laid-Open No. 06-015861 (1994) is used to acquire the glossiness data on print media, the measured quantities of light regularly reflected by different types of print media may be equivalent to each other. Further, new types of print media will be developed in the future and tend to have various reflection characteristics. Accordingly, with an apparatus that identifies the types of print media using an identifying device that utilizes only visible light or infrared light, it is impossible to accurately identify the types of media having similar glossiness. This may result in an incorrect identification.